Tens of thousands of unsolved crimes could be cracked with a new forensic technique, it was claimed today.

The Forensic Science Service is piloting a computer-based analysis system which can interpret previously unintelligible DNA samples.

Government-owned FSS claims the technique is a world first which will boost crime detection rates by more than 15%.

It allows scientists to pinpoint DNA samples when more than one individual has touched a surface, where only small amounts of DNA have been left behind or only poor quality material was found.

The new technique, DNAboost, will lead to scientists identifying 40% more samples than at present, an FSS spokeswoman said.

It is being put into practice by police in West Yorkshire, South Yorkshire, Northumbria and Humberside.

FSS scientists believe DNAboost could be the key to solving countless "cold cases" which have lain dormant in police files when it is combined with existing techniques, allowing a DNA match from minute samples.

An FSS spokeswoman said using the two systems in tandem could double the number of cold cases that could be solved.

FSS DNA manager Paul Hackett said: "We've been able to demonstrate an increased rate of interpretation even in those areas that have proved traditionally most difficult - fragments of cellular submissions.

"This means a great many more cases have the potential to be solved and a great many more families could look forward to securing justice."

The FSS can already handle more than 10,000 DNA crime stain samples each month and about 50,000 DNA samples from individuals. The pilot will run for three months, after which it is due to be extended to remaining police forces.